Blade grind angles

knotslip

knotslip

Joined
Mar 4, 2009
Messages
139
Hello-

I am new and ready to start grinding my first blade but I am stumped as to how to determine the correct blade grind angle...Is there a formula or method for figuring this? I'm using 1/8" steel and it has a height of 1 1/4". I want to do a full flat grind but I can't figure out what angle I should start grinding at on each side.????

Any help is greatly appreciated.

Thanks. :)
 
To go all the way from 1/8" to a 0 thickness, you have to use sine, cosine, and tangent.

In this case, you'd want about 2.862405226 degree angle on both sides.
 
Barring the use of machinery capable of holding the steel at a set angle until the desired thickness is achieved, I do it(as I believe most makers do) by hand, starting with a steeper grind and working the original grind backwards towards the spine. That allows you control over each area of the blade, making it possible to vary the grind as you'd like. It does take some practice, though:D
 
grind at 45 degree until you get your edge established.you can then walk the grind up to wherever you want.once you have the edge lined it,just keep pulling edge toward you until its at the height you want.
 
I tried to do the same thing when I first started: determine the correct angle and grind to it. This works great if you are milling your blades; however, grinding is a different story. Typically for a full flat grind, you start with a 45 degree or so bevel to soften the edge and thin in close you your desired edge thickness prior to heat treating (around 1/32"...a little thicker than that at this point). From there, you begin "walking" the bevel up the blade until it reaches the spine. Once that is done, you will have your correct angle, and if done well, it will be the same on both sides.

Don't worry about figuring out the angle from the very first and then trying to match it. I even went as far as to cut a block of wood to the correct angle and trying to use it as a rest for the blade to hold the correct angle all the way through. Once I figured out that you set a bevel and then walk it slowly up towards the spine (by grinding on your established bevel and placing more pressure on the spine side), things simplified greatly. It will take practice. Don't expect your first full flat grind to be perfect. Use it as a learning experience. Grind 10 or 15 blades of the same size and shape, and you'll really start to get the idea.

--nathan
 
Great. Thanks guys. I have lots of practicing to do. :)

When you say to grind a 45 degree bevel and work up to the spine - you mean to grind at 45 degrees at the bottom like a half inch or less up like Im doing a saber grind - then work that up to the spine using smaller and smaller angles? Just want to make sure I am on the same page here.

Thanks again!
 
Yep. You don't want to take it all the way to a sharp edge, just grind the 45 degree bevel on each side in, then slowly push the spine of the knife ever closer to the platen. Use a light touch, remember-'slow is smooth, smooth is speed':D Don't be in a hurry, plan on putting a couple of hours in standing in front of that grinder:)
 
Great! Thanks a lot for the great responses and quick ones at that. I'll be sure to let you know how it turns out. :) Lucky I am using annealed 1080 and not something harder - I think that would equal more time at the grinder. :)

Thanks again everyone!
 
Grind the initial bevel at 45 degrees to the edge on both sides. Then "walk" the grind toward the spine by grinding the side of the blade without letting the edge to touch the belt. Remember that you are grinding away the part that is not a knife. This gap is very small. Pay close attention as you go back and forth and keep that little gap the same width each time. Grind a pass and then look at the knife. Repeat. As you go you will understand. I apologize for my poor explanation, but once you start the process will reveal itself. Good luck.
 
silver_pilate said:
I tried to do the same thing when I first started: determine the correct angle and grind to it. This works great if you are milling your blades; however, grinding is a different story. Typically for a full flat grind, you start with a 45 degree or so bevel to soften the edge and thin in close you your desired edge thickness prior to heat treating (around 1/32"...a little thicker than that at this point). From there, you begin "walking" the bevel up the blade until it reaches the spine. Once that is done, you will have your correct angle, and if done well, it will be the same on both sides.

Don't worry about figuring out the angle from the very first and then trying to match it. I even went as far as to cut a block of wood to the correct angle and trying to use it as a rest for the blade to hold the correct angle all the way through. Once I figured out that you set a bevel and then walk it slowly up towards the spine (by grinding on your established bevel and placing more pressure on the spine side), things simplified greatly. It will take practice. Don't expect your first full flat grind to be perfect. Use it as a learning experience. Grind 10 or 15 blades of the same size and shape, and you'll really start to get the idea.

--nathan
Click to expand...

Ditto
Well said.
 
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